def chisl(s):
    k=''
    if s == 'zero':k='0'
    elif s =='one':k='1'
    elif s == 'two':k='2'
    elif s == 'three':k='3'
    elif s == 'four':k='4'
    elif s == 'five':k='5'
    elif s == 'six':k='6'
    elif s == 'seven':k='7'
    elif s == 'eight':k='8'
    elif s == 'nine':k='9'
    return k

prost = [101,103,107,109,113,127,131,137,139,149,151,157,163,167,173,179,181,191,193,197,199,211,223,227,229 ,233 ,239 ,241 ,251 ,257 ,263 ,269 ,271 ,277 ,281 ,283 ,293 ,307 ,311 ,313 ,317 ,331 ,337 ,347 ,349 ,353 ,359 ,367 ,373 ,379 ,383 ,389 ,397 ,401 ,409 ,421 ,431 ,433 ,439 ,443 ,449 ,457 ,461 ,463 ,467 ,479 ,487 ,491 ,499 ,503 ,509 ,521 ,523 ,541 ,547 ,557 ,563 ,569 ,571 ,577 ,587 ,593 ,599 ,601 ,607 ,613 ,617 ,619 ,631 ,641 ,643 ,647 ,653 ,659 ,661 ,673 ,677 ,683 ,691 ,701 ,709 ,719 ,727 ,733 ,739 ,743 ,751 ,757 ,761 ,769 ,773 ,787 ,797 ,809 ,811 ,821 ,823 ,827 ,829 ,839 ,853 ,857 ,859 ,863 ,877 ,881 ,883 ,887 ,907 ,911 ,919 ,929 ,937 ,941 ,947 ,953 ,967 ,971 ,977 ,983 ,991 ,997]
s1,s2,s3 = input().split()
a1,a2 = 0,0
num = int(chisl(s1)+chisl(s2)+chisl(s3))
for x in range(len(prost)):
    if prost[x]>num:
        a2 = x
        a1 = x-1
        break
    
if abs(prost[a1] - num)> prost[a2] - num:
    print(prost[a2])
elif abs(prost[a1] - num) <= prost[a2] - num:
    print(prost[a1])